A haze of smoke hangs over that whole war. Because neither dictatorship permits news coverage, the bloodiest conflict of our time is off the scope of our attention. Battle deaths are estimated at a million.

Iran is suffering more, but can win a war of attrition. Iraq, which started the war, cannot settle it short of surrender, because the Ayatollah Khomeini is determined to win no matter how many boys` lives he must squander.

Because Iran cannot launch a successful invasion in the south, it has begun to move in the north, enlisting the aid of oppressed Iraqi Kurds there. In response, Iraq has targeted Iran`s oil-shipping center at Kharg Island, hoping to cut down the 2-million-barrel-a-day oil shipments from there that are financing its opponent`s war.

If this is even partially successful, the ayatollah will strike at the Arab world`s support of his Arab enemy, Saddam Hussein of Iraq.

The ayatollah has at least three choices. He can use the 150,000 Iranian pilgrims now in Saudi Arabia during the Hajj religious season to tear up the host country; attack pipelines and tankers carrying oil from Iraq, Kuwait, Bahrain or anywhere in the Arab world; avenge Kharg by attacking the Saudi oil export facility at Ras Tanurah.

What does all this have to do with us? The concern of most Americans is on the price of gasoline at the pump. If this escalation continues, oil prices will stop declining for a time, adding to inflation, perhaps leading to a reduction of Arab financing of the U.S. debt, causing higher interest rates.

On the whole, however, Americans react to the Iran-Iraq war as the dying Mercutio did toward the squabbling Montagues and Capulets: ``A plague o` both your houses!``

That unconcern is a mistake. A strategic challenge may be in the making, and we should prepare for it.

Assume the war goes on. In Iran, where male children are a family`s only security in old age, resistance is sure to rise to the continued conscription of youths for slaughter, providing a counterweight to fanaticism. As of now, most of the organized resistance to Khomeini inside Iran is strongly leftist. If Iranian antiwar sentiment grows, or if Khomeini dies, the temptation to the Soviet Union cannot be ignored. The czarist dream of a warm-water port is still cherished by the Kremlin, and an uprising in volatile Iran would offer Mikhail Gorbachev the chance to make that ancient Russian dream come true.

The port is Chahbahar, on the Persian Gulf, leading to the Indian Ocean. It is as desirable to the Russians as Danzig was to the Prussians. In time of turmoil, the Red Army could move down from its troubled base in Afghanistan, or roll its tanks from the Soviet Union through the part of Iran known as Baluchistan.

We can hope that the U.S. has a contingency plan ready to meet a conventional Russian military move down through Iran. It would be good to hear a reminder that we would interpret a Soviet attempt to take advantage of unrest in Iran with a territorial grab as a threat to our ally Pakistan.

The more subtle danger, for which we are far less prepared, is for the Soviet Union to arrange for a separatist movement of the Baluchis. Comes the revolution, and the Baluchis set up in Chahbahar and invite their Russian sponsors down, are we ready to sponsor a force inside or outside Iran to stop them?

From a single, megadeath war, big conflagrations can start. To avert miscalculation, we should make certain that the other big bystander knows what we are prepared to do.